gray=imread();
subplot(2,2,1),imshow(gray),title("原图");
h=fspecial("log",5,0.6);
log1=imfilter(gray,h);
subplot(2,2,2),imshow(log1),title("log sigma=0.6");

h=fspecial("log",5,1);
log2=imfilter(gray,h);
subplot(2,2,3),imshow(log2),title("log sigma=1");
h=fspecial('laplacian');
lap=imfilter(gray,h);
subplot(2,2,4),imshow(lap),title("Laplacian");